1. Field of the Invention
The present invention relates to a tilt angle detection device and a method for detecting a tilt angle, which is defined as the angle between the normal on a recording surface of an optical recording medium at a position of irradiation of a light beam and the optical axis of the light beam.
2. Description of the Related Art
In order to read recorded data correctly from an optical recording medium such as an optical disk, it is necessary to irradiate a reading beam perpendicularly onto the recording surface of the optical recording medium. However, when warping occurs in the optical recording medium, or when the error in the mechanical system is too great, the reading beam cannot be irradiated perpendicularly onto the recording surface of the optical recording medium, reducing the precision of data reading.
For this reason, a recorded information reproduction device that reproduces recorded information from an optical recording medium detects the inclination (tilt angle) that occurs between a pickup (data reading means) and the optical recording medium with a tilt angle detection device, and restricts reduction in the precision of data reading by carrying out tilt correction processing, in which the entire pickup is inclined in response to the amount of detected tilt.
However, in the conventional tilt angle detection device, there is a problem that a higher equipment cost are involved and equipment becomes more complicated since a tilt detection mechanism such as a tilt sensor is especially required to detect the tilt that occurs between the pickup and the optical recording medium. Furthermore, there is another problem that, at the stage of manufacturing tilt servos, it is necessary to provide an adjustment process in which the tilt detection mechanism is properly adjusted, and that adjustment process is comparatively time-consuming and intricate.